Field of the Invention
The invention relates to systems and methods for inferring the shelf life or the freshness of one or more perishables when the perishables are monitored intermittently throughout their lives or when a perishable is monitored as part of a group of perishables having varying shelf lives. The invention relates to shelf life monitoring sensors and tags, the absence of shelf life monitoring sensors and tags during time periods in a perishable's life, and the perishable packaging, software, systems and processes for monitoring, inferring, estimating and analyzing the shelf life of a perishable product during the time the perishable is away from a monitoring device.
Description of the Related Art
Perishable products, whether produce, meats, fish, pharmaceuticals, blood, chemicals, flowers and other products, each have a unique shelf life. This shelf life is affected by the physical, chemical or biological characteristics of the perishable as well as the packaging of the perishable. Temperature is usually the predominant factor in determining shelf life—with humidity, vibration shock and other factors playing a lesser but important role.
For the last forty years the Use-by or Expiration date printed on a label in words and often supplemented by a barcode has been the predominant label for indicating the end time of a perishable. This date represents the perishable manufacturer's assessment of the temperature and other environmental conditions to be experienced by the perishable from the time it is manufactured until it is used. Because temperature is often different from what was predicted, the date alone is not always an accurate representation of shelf life. If a product is properly transported and stored, it can last much longer than the date. Conversely, if the temperature is higher than predicted, the product deteriorates more quickly in relation to temperature.
Digital shelf life monitoring labels and devices have been developed for the purpose of supplementing or replacing the paper expiration date. In reference to the use of shelf life sensors and labels to determine shelf life, U.S. Pat. Nos. 5,442,669 (Medin), 7,495,558 B2 (Pope), 7,764,183 B2 (Burchell), and 7,982,622 B2 (Burchell) are cited, assigned to Infratab. These patents describe how electronic temperature sensors and labels are used to monitor the shelf life or freshness of a perishable using freshness determining tables in conjunction with temperature sensors to calculate shelf life used and shelf life left of a perishable.
U.S. Pat. No. 5,442,669, Medin, describes a digital shelf life monitor which integrates time and temperature using a freshness determining table based upon spoilage characteristics of a perishable to calculate shelf life used and an LCD gauge for displaying shelf life left. U.S. Pat. No. 7,495,558 B2, Pope et al., adds RFID to the freshness determining table and describes a tag configuration in which sensing is separate from the RFID transponder so as to enable various shapes and sizes of tag and flexibility in support of various RF frequencies. It also adds humidity, vibration and other sensors to both its freshness monitoring and to its freshness determining tables and includes methods of inheriting shelf life from a sensor tag to another sensor tag or an identification tag. U.S. Pat. No. 7,982,622 B2, Burchell et al., adds the use of light and audio to identify items based upon shelf life and describes different physical configurations supported by the two module sensor architecture of the tag.